The US announced new sanctions against what a "network of petroleum shipments" to Syria, including Russian and Iranian companies and individuals, in what Washington said was an attempt to disrupt shipments to Syrian-owned ports. Six individuals and three institutions were sanctioned in what the Treasury said was an illicit plot involving officials in Iran working with Russian companies to send millions of barrels of oil to the Assad government in exchange for funds that Tehran then used to fund Islamic militant groups Hamas and Hezbollah.

Those sanctioned include two officials working with the Central Bank of Iran, a Syrian national and his Russia-based company Global Vision Group, and Russia’s state-owned Promsyrioimport, a subsidiary of the Kremlin’s energy ministry, as well as its first deputy director. The administration is also sanctioning an Iranian entity that purports to be a medical and pharmaceutical company that U.S. officials say has been repeatedly used to facilitate illicit money transfers in the scheme.

“Today we are acting against a complex scheme Iran and Russia have used to bolster the Assad regime and generate funds for Iranian malign activity,” Treasury Secretary Steven Mnuchin said in a statement. “Central Bank of Iran officials continue to exploit the international financial system, and in this case even used a company whose name suggests a trade in humanitarian goods as a tool to facilitate financial transfers supporting this oil scheme."

As detailed in the Treasury statement, Russian companies would act as middlemen, taking money from Iran to move the oil to Syria. In one case detailed in a Treasury Department press release, the Iranian central bank transferred money to an Iranian pharmaceutical company, hoping that its humanitarian name would throw US observers off the trail. That money was then allegedly wired to a Russian bank, then to a Russian company that shipped the oil from Iran to Syria. Along the way, the Treasury Department claims that Russian ships would switch off their GPS tracking systems to conceal the origin of their cargo.

Once the cash is stashed in the Central Bank of Syria, it is then allegedly sent to Hezbollah and Hamas units operating in Lebanon and on Palestinian territory.

Trump administration officials said Syria sent hundreds of millions of U.S. dollars to Iran’s Islamic Revolutionary Guards Corps Quds Force in return for the oil shipments, money that was then used to fund Hamas and Hezbollah.

Officials described the action as the latest effort to ratchet up pressure on Iran for its “destructive and destabilizing behavior” beyond the reimposition of sanctions lifted under the Obama administration as part of the Iranian nuclear deal. Trump announced his decision to withdraw from the deal in May and reinstated sanctions on Tehran earlier this month.

The latest sanctions build on an ongoing campaign against Iran and its allies, which target the country’s banking, shipping, and oil sectors. Banks that provided services to Hamas and Hezbollah were slapped with sanctions, as were shipping companies that moved Iranian troops and supplies around the Middle East.

As reported previously, facing the threat of US penalties, the SWIFT financial messaging system cut the Iranian central bank off from its network a week later, making it even more difficult for the country to settle its import and export bills.

The administration also issued a global maritime advisory warning those in the shipping industry that they run the risk of U.S. sanctions if they are involved in shipping oil to Syria. The US has promised that it will "disrupt" any attempted shipments to government-owned ports in Syria

Keeping up the Trump administration’s tough rhetoric on Iran, Treasury Undersecretary for Terrorism and Financial Intelligence, Sigal Mandelker, warned on Tuesday that “shipping companies, insurers, vessel owners, managers, and operators should all be aware of the grave consequences of engaging in sanctionable conduct involving Iranian oil shipments.”